JP2002325781A - Artificial joint implant member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a knee joint implant member which is enhanced in durability by additionally lessening the wear of the contact surfaces of a femur component and a tibia component of an artificial joint constituted in such a manner that the former component rolls and slides on the latter component. SOLUTION: The under surface portion of the femur component 1 is so formed as to have many open pores 11 by plasma thermal spraying of metallic powder, etc., and the top surface portion 2b of the tibia component 2 is formed of, for example, a PVA hydroged having elasticity and having many open pores 21. As a result, joint fluid is held at all times in the open pores 11 and in addition, when load from above is exerted to the components, the joint fluid held in the open pores 21 is squeezed out and a lubricating film is formed between the contact surfaces, by which the wear resistance between the contact surfaces is lowered.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used to restore a knee joint that has been highly deformed due to rheumatoid arthritis, osteoarthritis or the like or a joint that has been destroyed due to a traffic accident, disaster or the like to a normal function. It relates to an artificial knee joint.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG.
And a tibial component 2 are inserted and fixed, respectively, and a knee joint replacement operation is performed. In order to reproduce a normal joint motion of a person, the lower surface of the femoral component 1 rolls and / or contacts the upper surface of the tibial component 2 while contacting the upper surface. Knee implant members (1, 2) have been used that have a structure that allows them to bend by sliding. The lower surface of the femoral component 1 is formed of a metal material having excellent mechanical strength for load resistance, and the upper surface of the tibial component 2 is more elastic than the metal material for shock absorption and reduction of wear, and has abrasion resistance. In most cases, it was formed of ultra high molecular weight polyethylene having a low coefficient of friction.

[0003]

Since the durability of the above-mentioned artificial knee joint is limited by the wear of the sliding portion, conventionally, the sliding portion where the femoral component and the tibial component are in contact with each other is mirror-finished to provide friction resistance. Inventions have been devised to minimize power and increase durability. However, even with this ingenuity, the ultra-high molecular weight polyethylene gradually wears, and the knee joint implant member fails to heal to the living bone, and the accumulation of wear powder in the living body causes a foreign body reaction in living cells. The problem was not completely solved, leaving room for improvement.

[0004] In view of the above-mentioned circumstances, an object of the present invention is to provide a knee joint implant member having improved durability by further reducing wear of a sliding portion.

[0005] The knee joint implant member (1,
In 2), the lower surface of the femoral component 1 rolls or slides while contacting the upper surface of the tibial component 2, thereby exhibiting a function as a knee joint. The load from the femoral component 1 is transmitted to the tibial component 2 through the contact surface with the tibial component 2, but the two components 1 and 2 are not always in contact at the same place, and the contact surface moves. While rolling and sliding. Therefore, if a sufficient amount of synovial fluid C is constantly supplied to the contact surface, the lubrication of the contact surface suppresses wear of the contact surface.

According to the classic lubrication theory, it has been considered that the synovial fluid is drawn into the gap between the joint surfaces by the relative movement of the joint surfaces of the living joint, and the lubricating action by the fluid pressure prevents wear. However, in order for this theory to be valid, high-speed relative motion is required on both joint surfaces,
The actual articulation of the living body is intermittent and the relative movement speed between the two joint surfaces is small, and therefore cannot be explained by this theory.

On the other hand, McCutchen has a self-induced lubrication mechanism in living joints, that is, when both joint surfaces are pressed together, synovial fluid is squeezed out from the cartilage covering both joint surfaces, and the synovial fluid is injected into the gap between both joint surfaces. A theory was proposed in which leaching lubrication to form a film acts to prevent wear (CW McC).
utchen: "The Frictional Pr
operations of Animal Join
t ", Wear, vol. 5 (1962) p.
reference).

The present inventors have worked diligently on the research and development of an artificial knee joint capable of simulating the leaching lubrication action of a living joint based on the McCutchen theory, and completed the present invention. .

[0009]

The present invention comprises a femoral component fixed to a femur and a tibial component fixed to a tibia, wherein the lower surface of the femoral component contacts the upper surface of the tibia component. A knee joint implant member configured to roll and / or slide, wherein the knee joint implant member has a plurality of open pores in a lower surface of the femoral component.

According to a second aspect of the present invention, the knee joint according to the first aspect is characterized in that the upper surface of the tibial component has elasticity and / or has a large number of open pores. It is an implant member.

According to a third aspect of the present invention, there is provided a first artificial bone component fixed to one living bone constituting a living joint, and a second artificial bone component fixed to the other living bone. An artificial joint implant member wherein one artificial bone component is configured to roll and / or slide while contacting a second artificial bone component, wherein the artificial bone component has a large number of open pores at a contact surface of the one artificial bone component. And the contact surface of said other artificial bone component is resilient, and / or
Or, it is an artificial joint implant member characterized by having a large number of open pores.

As shown in FIG. 1, the femoral component 1 of the present invention has a large number of open pores 11 on its lower surface (surface in contact with the tibial component). Even if the contact surface is changed due to rolling or sliding while the joint fluid is contained, the joint fluid contained in the open pores existing on the new contact surface exerts a lubricating effect. Thus, wear of both components, particularly the tibial component 2, is suppressed.

On the other hand, when a conventional mirror-finished femoral component is used, there are almost no open pores on its surface, and it cannot retain synovial fluid, so that lubricating action is small and abrasion is sufficiently reduced. It could not be suppressed.

As shown in FIG. 2, in addition to the provision of the open air holes 11 on the lower surface of the femoral component 1, the upper surface (the surface in contact with the femoral component 1) 2b of the tibial component 2 is made elastic. By having a certain number of open pores 21, the above McCutch
The effect similar to that of cartilage described in the theory of en further amplifies the lubricating effect. That is, when the tibial component upper surface portion 2b is elastically compressed by the load from the femoral component 1, the synovial fluid held inside the open pores 21 is squeezed out, and this synovial fluid is combined with the femoral component 1. By forming a lubricating film between the contact surfaces of the tibial component 2, the lubricating effect is amplified. On the other hand, when the load from the femoral component 1 is removed, the surrounding synovial fluid is absorbed and held in the open pores 21 when the upper surface portion 2b of the tibial component elastically returns to the original thickness. Thus, by using the knee joint implant member of the present invention, similar to a living joint, when a load is applied to a joint, the joint fluid is released to enhance the lubricating effect, while absorbing the joint fluid when the load is removed. -It is possible to have a self-originating lubricating action to hold, thereby further improving the wear resistance of the contact surface. As described above, the upper surface of the tibial component preferably has both elasticity and a large number of open pores. It serves to replenish synovial fluid between the lower surface and the upper surface of the tibial component.

The configuration shown in FIG. 2 can be expected not only for the artificial knee joint but also for other artificial joints.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a knee joint implant member according to the present invention will be described below.

First, a method of providing open pores to the lower surface of a femoral component according to the present invention will be described. For example, a particle diameter of 1 is applied to the surface of a titanium, titanium alloy or ceramic femoral component base material by plasma spraying.
Co-Cr alloy powder of 00 to 350 μm and particle size of 44 μm
By welding a mixed powder of the following Co-Cr alloy powder, open pores are formed on the surface of the base material. Although not particularly limited, open pores having an average diameter of 40 to 100 μm and an average depth of 5 to 1000 μm are formed at an area ratio of 20 to 2 μm.
The formation of 5% is preferable because a proper amount of synovial fluid can be retained on the surface of the femoral component without reducing the mechanical strength of the femoral component.

Here, the average diameter, average depth, and area ratio of the open pores were determined by an image analyzer. In particular,
First, an arbitrary observation area is selected from the sprayed surface, the diameter and area of each open pore included in this observation area are measured by an image analyzer, and the arithmetic average value of the individual open pore diameters is calculated as the average of the open pores. The ratio of the total area of the individual open pores to the area of the observation region was defined as the area ratio of the open pores. In addition, for any cross section of the sprayed surface, similarly to the above, select an arbitrary observation region and measure the depth (length) of each open pore included in this observation region with an image analyzer,
The arithmetic average value was defined as the average depth of the open pores.

The method of providing open pores on the lower surface of the femoral component is not limited to the plasma spraying method. For example, the open pores may be formed by machining or laser processing the surface of the base material of the femoral component. A forming method or the like may be used.

It is also preferred that the lower surface of the femoral component is mirror-finished after the opening (formation) of the open pores, because the frictional resistance of the contact surface is further reduced, wear is suppressed, and durability is further improved.

Next, a method for imparting elasticity and open pores to the upper surface of the tibial component according to the present invention will be described.
For example, a layer of resilient, open-pore (porous) polyvinyl alcohol (PVA) hydrogel is integrally formed on the surface of a tibial component substrate made of ultra-high molecular weight polyethylene. Although not particularly limited, the elasticity of the formed PVA hydrogel layer is 1 to 25 MPa in longitudinal elastic modulus (Young's modulus), the open pore area ratio on the layer surface is 30 to 70%, and the layer thickness is 2 to 2. The range of 2.5 mm is preferable because the effect as a buffer against a load and the effect of releasing, absorbing, and retaining synovial fluid in accordance with the degree of the load can be exhibited more appropriately while being compatible.

The longitudinal elastic modulus is a value measured by compressing / tensifying a circular thin film of PVA hydrogel using a compression test apparatus. According to the same measurement method and definition.

In actually implanting and installing the knee joint implant member of the present invention in a patient, a method of bonding to the remaining living bone using a bone cement such as polymethyl methacrylate, or using no bone cement A well-known technique used for a conventional knee joint implant member may be appropriately adopted, such as a method of making the surface of a knee joint implant member uneven and penetrating and fixing living bone.

It is apparent that the present invention can also be applied to an artificial joint implant member used for a joint other than the knee joint by the same method as the above-described knee joint implant member. For example, it can be used for a hip joint or an elbow joint, and when a tibial implant member itself is divided into two members (for example, a base portion and an upper surface portion) in a knee joint and is configured to roll or slide, It is also possible to apply to parts.

[0025]

According to the first aspect of the present invention, since the lower surface of the femoral component always contains the synovial fluid, the lubricating action of the lower surface of the femoral component reduces wear of the contact surface between the two components, particularly the upper surface of the tibial component. Can be suppressed.

According to the second aspect of the present invention, in addition to the above effects, the upper surface of the tibial component can be provided with a self-induced lubricating action, and the wear of the contact surface can be suppressed.

According to the third aspect of the invention, the same effect as in the second aspect can be expected not only in the artificial knee joint but also in other artificial joints.

That is, according to the present invention, a highly durable artificial joint having excellent wear resistance can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing the relationship between components of a knee joint implant member of the present invention (claim 1).

FIG. 2 is a cross-sectional view showing the relationship between components of a knee joint implant member according to the present invention (claim 2).

FIG. 3 is a cross-sectional view illustrating a state where a conventional knee joint implant member is attached to a living body.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Femur implant member 11 ... Open pore 2 ... Tibial implant member 2a ... Base part 2b ... Upper surface part 21 ... Open pore A ... Femur B ... Tibia C ... Synovial fluid

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Yasutoshi Takano 1-3-18, Wakihama-cho, Chuo-ku, Kobe-shi, Hyogo Kobe Steel, Ltd. Kobe Main Office (72) Inventor, Takuzo Iwatsu Kita, Hyogo Prefecture 4-1-2-15 Kimikage-cho, Ward (72) Inventor Mitsumasa Matsuda 4-37-1-609 (72) Inventor Suuchu Aneta Nicoleta 3-1-30 Shimodori, Nada Ward, Kobe City, Kobe City, Hyogo Prefecture Inventor Masahiro Kurosaka 5-14-15 Sumiyoshi Yamate, Higashinada-ku, Kobe-shi, Hyogo F-term (reference) 4C097 AA03 BB01 CC13 CC17 SC01

Claims (3)

[Claims] 1. A femoral component secured to a femur and a tibial component secured to a tibia,
A knee joint implant member configured such that the lower surface of the femoral component rolls and / or slides while being in contact with the upper surface of the tibial component, wherein the lower surface of the femoral component has a plurality of open pores. A knee joint implant member, characterized in that: 2. The knee implant member according to claim 1, wherein the upper surface of the tibial component has elasticity and / or has a plurality of open pores. 3. A first artificial bone component comprising a first artificial bone component fixed to one living bone constituting a living joint and a second artificial bone component fixed to the other living bone. Is configured to roll and / or slide while in contact with a second artificial bone component, wherein the artificial joint implant member is configured to have a large number of open pores in a contact surface of the one artificial bone component. An artificial joint implant member, characterized in that the contact surface of the other artificial bone component has elasticity and / or has a large number of open pores.